5WORSTER R. Nature Economoy:History of Ecological Ideas [ M ], Cambridge: Cambridge University Press, 1985.
6BUELL, L. "Thoreau and the Natural Environment"[A] . in Joel Myerson ed. The Cambridge Companion to Henry David Thoreau, [ C]. Cambridge: Cambridge University Press, t995.
7HARDING, W. The Days of Henry Thoreau: A Biography[M]. Dover:Dover Publications Inc., 1982.
8梭罗.瓦尔登湖[M].徐迟译.长春:吉林人民出版社.1997
9THOREAU, H. D. "Ktaadn". The Maine Woods[A]. in Henry David Thoreau [M] . The Library of America. 1985.
10MCGREGOR, R. K. A Wider View of the Universe: Henry Thoreau' s Study of Nature [ M ] . Urbana: University of Illinois Press, 1997.